[Frequency of improper diagnosis of hypertension]

The aim of this work is to estimate the real prevalence of hypertension in a population declared hypertensive by general practitioners. This prospective study has lasted 30 months from October 1994 to March 1997). It has concerned 2,151 patients that had been declared hypertensive by general practitioners. Each patient had 2 visits at 15 days interval. During each visit the blood pressure (BP) is measured 4 times at 5 min interval with a mercury tensiometer. The patient remains supine for 20 min. Patients declared normotensive on these 8 measurements are controlled once every 6 months. Those that are declared hypertensive are distributed in 2 groups: the patients that have a systolic blood pressure (SBP) superior to 160 mm of mercury (mmHg) and/or diastolic blood pressure (DBP) superior to 95 mmHg are treated with the habitual follow-up. Those that have a SBP and DBP between 140-160 mmHg and 90-95 mmHg have a control visit at the end of the first and the third month. After this period patients whose BP remains between 140-160 mmHg and 90-95 mmHg have an ambulatory blood pressure measurement (ABPM). This study included 1,635 women and 516 men. Average age was 54 +/- 11 years. The average of 8 measurements of SBP/DBP was 148.3 +/- 22.5/93 +/- 13 mmHg. After 8 measurements, out of 2,151 patients, 37.8% (841 patients) were declared normotensive and 62.2% (1,337 patients) had a SBP and/or DBP > 140/90 mmHg. This group was controlled after one month and 3 months. A subgroup (254 patients) was declared normotensive, and the 588 patients whose BP remained between 140-160 mmHg and 90-95 mmHg had an ABPM : 481 (48%) were then declared normotensive and 307 (52%) were declared normotensive patients. After repeated controls, with the use of ABPM, only 37.3% were truly hypertensive. This study confirms that a long follow-up is necessary before labelling a patients as hypertensive. BP can remain abnormal for weeks and months. A large group of "hypertensive" patients are normotensive people with a white coat effect or so labelled because of errors in technique or the absence of a sufficient delay so that BP returns to normal.